The present invention relates generally to a mixture and method for producing a ceramic-glass-ceramic seal by the use of microwave heating.
Conventional sealing of ceramics has been done by use of resistant heating furnaces, which consume relatively large quantities of energy, time and manpower while subjecting the ceramics to rather hostile environments. An alternative method of producing seals was disclosed in U.S. Pat. Nos. 4,529,856 and 4,529,857 for ceramic-glass-metal and ceramic-glass-ceramic materials respectively. These seals were formed by subjecting a slurry comprising a coupling agent, such as watch oil, and a sealing material, such as glass, evenly spread between the ceramic and ceramic or metal substrates, to microwave energy in order to cause heating and formation of the seal. Although this use of microwave energy represented an improvement over the conventional resistant heating furnace method, problems still remained in that the final temperature of the sealing material never went beyond 700.degree.-800.degree. C. It was thought this was due to the need to raise the sealing glass temperature high enough so that the sealing glass itself could better couple to the microwave energy instead of being largely transparent to the microwaves.
Therefore it is an object of the present invention to provide an improved method of forming ceramic-glass-ceramic seals.
It is the further object of the present invention to provide an easily automated, low energy, efficient, fast, and effective method for forming ceramic-glass-ceramic seals at temperatures exceeding 800.degree. C.
It is yet another object of the present invention to provide ceramic-glass-ceramic seals with an improved microstructure and strength.